The crystal structure at 1.54 A resolution of a double mutant of interleukin-1beta (F42W/W120F), a cytokine secreted by macrophages, was determined by multiple-wavelength anomalous dispersion (MAD) using data from highly twinned selenomethionine-modified crystals. The space group is P4(3), with unit-cell parameters a = b = 53.9, c = 77.4 A. Self-rotation function analysis and various intensity statistics revealed the presence of merohedral twinning in crystals of both the native (twinning fraction alpha approximately 0.35) and SeMet (alpha approximately 0.40) forms. Structure determination and refinement are discussed with emphasis on the possible reasons for successful phasing using untreated twinned MAD data.
Use of multiple anomalous dispersion to phase highly merohedrally twinned crystals of interleukin-1beta.,Rudolph MG, Kelker MS, Schneider TR, Yeates TO, Oseroff V, Heidary DK, Jennings PA, Wilson IA Acta Crystallogr D Biol Crystallogr. 2003 Feb;59(Pt 2):290-8. Epub 2003, Jan 23. PMID:12554939
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